1. Field of the Invention
The present invention relates to an optical transceiver that is removable from a host device, performs an optical transmitting and receiving operation to receive an electrical signal from the host device, convert the received electrical signal into an optical signal and transmit the converted optical signal to an external, and to receive an optical signal from the external, convert the received optical signal into an electrical signal, and transmit the converted electrical signal to the host device, under the condition that the optical transceiver is attached to the host device. The invention more particularly relates to an optical transceiver capable of managing a history record indicating the operation of the optical transceiver.
2. Background Art
In optical communications using an optical fiber, an optical transceiver that transmits and receives an optical signal is widely used. The optical transceiver is designed based on an industrial standard called Multi-Source Agreement typified by XFP and SFP in many cases. Thus, many of optical transceivers have unified interfaces and unified functions when seen from the externals of the optical transceivers. In contrast, the internal designs of the optical transceivers depend on design concepts of the manufacturers.
The optical transceiver uses its internal functions to detect information such as a power supply voltage applied to the optical transceiver, an internal temperature of the optical transceiver, a bias current applied to a laser, a monitor current applied to a laser, and power of received light and to write the information in a memory, and has a function for monitoring the information in some cases (see, e.g., Patent Document 1). In addition, the optical transceiver has an alarm function for providing a warning and an alarm to an external of the optical transceiver when a parameter indicative of the operational state of the optical transceiver exceeds a specified threshold value in some cases. When the optical transceiver has the alarm function, five memory areas, in which the parameter indicative of the operational state, a first threshold value, a second threshold value, a warning state flag, and an alarm state flag are respectively written, are allocated to the optical transceiver (see, e.g., Patent Document 2). The monitoring function and the alarm function are called digital diagnostic monitoring (DDM).    [Patent Document 1] Japanese Laid-Open Patent Publication No. 2006-191681    [Patent Document 2] Japanese Translations of PCT for Patent No. 2007-535242
In recent years, an optical transceiver (such as a SFP transceiver, a SFP+ transceiver, a XFP transceiver, a XENPAK transceiver and an X2) removable from a host device has been used. After the removable optical transceiver is attached to a host device and used, the removable optical transceiver is attached to another host device and reused. However, the conventional optical transceiver is not capable of managing an operation history record indicating when the optical transceiver starts an operation and an operation history record indicating when the optical transceiver terminates the operation.